Topic 7 Part 2 Gene therapy

Question 1

Gene therapy

Answer 1

The treatment of disease using the instructions encoded within genes to: (1) Replace or repair a defective gene that is causing disease; (2) Provide a new or changed function to a cell.

Question 2

In vivo gene therapy

Answer 2

1. Systemic (i.e., intravenous) delivery of the gene, delivering it to multiple affected tissues.
2. The ideal method, but there are problems with targeting tissues and controlling delivery.

Question 3

Ex vivo gene therapy

Answer 3

1. Tissue (e.g., blood, bone marrow, liver cells) is removed from the patient, the gene is added, and the tissue is replaced.
2. Currently the most common mode of gene delivery. Limited to one tissue at a time.

Question 4

Viral vector gene therapy

Answer 4

1. The use of viruses that are inactivated (removal of the genes that enable replication and pathogenesis) to deliver genes.
2. Enables specific cell binding and entry, efficient targeting of the transgene to the cell nucleus, and the ability to avoid intracellular degradation.

Question 5

The majority of gene therapy clinical trials have been focused on the treatment of _

Answer 5

Cancer.

Question 6

Severe Combined Immunodeficiency (SCID)

Answer 6

1. Autosomal recessive disorder affecting the white blood cells and immune system.
2. First human gene therapy involved insertion of “normal” ADA genes into the bloodstream by incubating patients’ white blood cells (leukapheresis) with the genes via a mouse retrovirus.

Question 7

Direct gene transfer for cancer treatment

Answer 7

1. Virus containing a toxin-producing “suicide” gene directly injected into a tumor.
2. Patients treated with a drug that activates the gene, causing the toxin to kill many tumor cells.
3. This can be used in addition to traditional cancer therapies such as chemotherapy and radiation.